Example - from class Magnitude

The relational operators, used for comparisons, are defined in
class Magnitude. If you look at these carefully you will notice
an interesting circularity. Less than or equal is defined in
terms of less than, and of equal. Greater than or equal in
terms of less than or equal. Less than in terms of less than
or equal and not equal. And so on. This would seem to necessarily
imply an infinite circularity.